How is a dating scan performed? A dating scan is carried out by ultrasound. A sonographer, who is usually a radiographer or a midwife trained in ultrasound, will complete your scan. If the scan is after 10 weeks, ultrasound recordings are usually made through your abdomen.

How does a dating ultrasound work?

Ultrasound can tell you how many weeks pregnant you are, based on the size of your fetus. Dating ultrasounds are most accurate when they happen between 7-12 weeks, and are calculated by measuring the fetus crown-rump length. This generally predicts the expected date of birth within 5 days.